The complete chloroplast genome of Caryopteris mongholica and phylogenetic implications in Lamiaceae

Caryopteris mongholica, which belongs to the mint subfamily Ajugoideae (Lamiaceae), has high ornamental and medicinal value. Previously published phylogenetic studies strongly support the monophyly of Lamiaceae, but some major relationships within the family still remain unclear. In this study, we report the chloroplast (cp) genome of C. mongholica and take advantage of several previously reported cp genomes from related taxa to infer phylogeny in Lamiaceae. The cp genome of C. mongholica is 151,707 bp in length, comprising a pair of inverted repeat regions (25,634 bp) separated by a large single-copy region (83,203 bp) and a small single-copy region (17,236 bp). The genome encodes 114 unique genes consisting of 80 different protein-coding genes, 30 transfer RNA and four ribosomal RNA genes, with 19 duplicated genes in the inverted repeats. The phylogeny reconstruction based on the complete genome sequences of 20 mint species strongly supports the placement of Ajugoideae as sister to (Lamioideae + Scutellarioideae), as well as the sister relationship between Premnoideae and Tectona.